The core principle of ClickOnce is to ease the deployment of Windows applications. In addition, ClickOnce aims to solve three other problems with conventional deployment models: the difficulty in updating a deployed application, the impact of an application on the user's computer, and the need for administrator permissions to install applications.
ClickOnce-deployed applications are considered "low impact", in that they are installed per-user, not per-machine. No administrator privileges are required to install one of these applications. Each ClickOnce application is isolated from the others. This means one ClickOnce application is not able to "break" another. ClickOnce employs Code Access Security (CAS) to ensure that system functions cannot be called by a ClickOnce application from the web, ensuring the security of data and the client system in general.
Applications may be bundled with the computer and its system software or published separately, and may be coded as proprietary, open-source or university projects.
In information technology, an application is a computer program designed to help people perform an activity. An application thus differs from an operating system (which runs a computer), a utility (which performs maintenance or general-purpose chores), and a programming tool (with which computer programs are created). Depending on the activity for which it was designed, an application can manipulate text, numbers, graphics, or a combination of these elements. Some application packages focus on a single task, such as word processing; others, called integrated software include several applications.